Cell culture of eukaryotic cells that is commercially relevant can be divided into two classes: the cell lines and the primary or stem cells. The cell lines are relevant for the preparation of vaccines (viruses) and of proteins, e.g., antibodies. The cell is used as a bioreactor, the cell is thus nothing else than a host. It can be genetically engineered: one introduces into the cell a gene sequence whose gene product one desires to be produced by the cells. This class of cells can be grown in a fixed bed bioreactor such as disclosed in WO 2007/039600A, the disclosure of which is incorporated herein by reference. When dealing with stem cells, the cells themselves can be harvested and are accordingly the product. The product can be used, for example, for regenerative medicine and for tissue engineering.
Experiments have shown that the culture of certain types of cells such as stem cells is much more delicate than the culture of cell lines, due to several factors. The cells turn out to be very sensitive to mechanical stresses and other external influences. Typical procedures in use in the production of cell lines both to expand and to harvest cells out from a bioreactor are often not appropriate for stem cells; they easily damage or kill all the stem cells.
Currently, stem cells are typically grown in stationary conditions, in tissues culture flasks, put in an incubator. For sake of clarity, “culture flasks” refers to all stationary culture devices, as T-Flasks, Petri dishes, Cell Factories Cell stacks and so on. Roller bottles are also associated with culture flasks. These stationary flasks are provided with a filter for gas exchange. The incubator comprises a plurality of T-flasks, each one constituting a substrate suitable for cell culture upon provision of adequate nutrition. Such systems have the disadvantage of being highly inefficient in terms of the available surface per unit volume. Moreover, the preparation of cell growth takes time: filling T-flasks occurs by inserting a dedicated liquid (e.g., dispersion, suspension or the like) comprising cells to be grown and nutrition, and thereafter turning the T-flask upside down once or more than once to distribute the cells over the available levels. In addition, this operation needs to be repeated several times for each batch/each patient, based on the number of T-flasks requested to produce the sufficient amount of cells needed for a treatment.
Accordingly, a need is identified for an apparatus that addresses the limitations of such devices and others.